This invention is related to a process for progressively forming a model of either a single multiple-panel sheet metal assembly or several assemblies having interfitting panels. A replica of each panel is formed in a cavity between a pair of machineable foam blocks. At least one of the foam blocks is then used to form the replica of an adjacent panel of either the same assembly or a close fitting panel of another assembly. The remaining panels are progressively formed and then attached together to form a carbon fiber model of the sheet metal assembly which may, for example, be a part of an automobile sheet metal assembly. The machined foam blocks can be used as tooling aids for making the dies for stamping the sheet metal panels.